1. Field of the Invention
The present invention relates, in general, to temperature detecting devices. More specifically, the invention relates to a temperature detecting device, having an infrared ray detector, which is used in cooking apparatuses such as microwave ovens to detect the temperature of food being cooked.
2. Description of the Prior Art
Cooking apparatuses, such as, e.g., microwave ovens, having a microcomputer are well known. A cooking apparatus of this type also has various sensors for detecting the temperature of food being cooked. The cooking apparatus may carry out a suitable cooking operation in accordance with the detection result of the sensors as the food is being cooked. In particular, an infrared ray detector generally is used as a sensor in this type of cooking apparatus. The infrared ray detector detects infrared rays from the food, and the microcomputer calculates the temperature of the food on the basis of the intensity of the infrared rays detected. The output of a magnetron (a heating source), therefore, may be controlled by the microcomputer in response to the temperature changes of the food.
The infrared ray detector, generally, is a type of optical sensor. The infrared ray detector is arranged above the food, for example, on the ceiling of a heating chamber, to receive infrared rays from the food.
In the system described above, a reduction in sensitivity of the infrared ray detector often occurs after long time use due to contamination such as grease from the food produced during cooking. The contaminant adheres to the incident surface of the infrared ray detector, and accumulation thereof reduces the intensity of infrared rays reaching the infrared ray detector from the food.